Locking collar stop

ABSTRACT

Disclosed herein is a collar stop configured for insertion into well production tubing where the collar stop provides an interference fit with a collar recess disposed between two adjacent sections of production tubing. The collar stop may be utilized to provide a bottom hole assembly at a desired location in a well bore. The collar stop device is configured to lock once positioned. Such locking prevents accidental removal during high fluid flows.

FIELD OF THE INVENTION

The present application generally relates to a plunger lift systems usedto produce hydrocarbon wells. More specifically, a locking collar stopis provided that may define a bottom of a plunger well where a seatingnipple is not utilized.

BACKGROUND

Well bores of oil and gas wells extend from the surface to permeablesubterranean formations (‘reservoirs’) containing hydrocarbons. Thesewell bores are drilled in the ground to a desired depth and may includehorizontal sections as well as vertical sections. In any arrangement,piping (e.g., steel), known as casing, is inserted into the well bore.The casing may have differing diameters at different intervals withinthe well bore and these various intervals of casing may be cementedin-place. Other portions (e.g., within producing formations) may not becemented in place and/or include perforations to allow hydrocarbons toenter into the casing. Alternatively, the casing may not extend into theproduction formation (e.g., open-hole completion).

Disposed within a well casing is a string of production piping/tubing,which has a diameter that is less than the diameter of the well casing.The production tubing may be secured within the well casing via one ormore packers, which may provide a seal between the outside of theproduction piping and the inside of the well casing. The productiontubing provides a continuous bore from the production zone to thewellhead through which oil and gas can be produced.

The flow of fluids, from the reservoir(s) to the surface, may befacilitated by the accumulated energy within the reservoir itself, thatis, without reliance on an external energy source. In such anarrangement, the well is said to be flowing naturally. When an externalsource of energy is required to flow fluids to the surface the well issaid to produce by a means of artificial lifting. One means ofartificial lift is plunger lift. A plunger lift system utilizes gaspresent within the well as a system driver. A plunger lift system worksby cycling a plunger into and out of the production tubing of the well.During a cycle, a plunger typically descends through the tubing to thebottom of a well passing through fluids within the well. Once theliquids are above the plunger, these liquids may be picked up or liftedby the plunger and brought to the surface, thus removing most or allliquids in the production tubing. The gas below the plunger will pushboth the plunger and the liquid on top of the plunger to the surfacecompleting the plunger cycle. In some instances, plunger lift may becombined with gas lift where air/gas is injected into the productiontubing to reduce the hydrostatic pressure within the tubing.

SUMMARY

Disclosed herein is a collar stop configured for insertion into wellproduction tubing where the collar stop provides an interference fitwith a collar recess disposed between two adjacent sections ofproduction tubing. The collar stop may be utilized to provide a bottomhole assembly at a desired location in a well bore. The collar stopdevice is configured to lock once positioned. Such locking preventsaccidental removal during high fluid flows.

In an arrangement, the collar stop is a generally cylindrical deviceconfigured for disposition within production tubing. The collar stopincludes a mandrel body and a casing engagement body. The casingengagement body forms a lower portion of the device and incudes an upperend having a central aperture. As used herein, upper and lower defineportions of the device as located in a vertical section of productiontubing. In an embodiment, the upper end is an annular ring having aninternal opening (e.g., central aperture) extending therethrough. Atleast first and second legs or arms extend (e.g., cantilever) downwardlyfrom generally opposing edges of the upper end (e.g., annular ring).Outside surface of each arm include a casing engagement tab configuredfor receipt in a collar recess between adjacent section of productiontubing. Such engagement tabs are typically located proximate to a freeend of each arm.

A mandrel body slidably engages the casing engagement body. In anarrangement, the mandrel body includes upper and lower mandrelsconnected by an axial rod, which passes through the central aperture inthe upper end of the casing engagement body. The lower mandrel isdisposed between the arms of the casing engagement body while the uppermandrel is disposed above the upper end of the casing engagement body.The mandrel body is configured to move relative to the casing engagementbody between a lower surface of the upper mandrel and an upper surfaceof the lower mandrel.

A mechanical connector is configured to lock the mandrel body in alowered or closed position where the upper mandrel is disposed proximateto the upper end of the casing engagement body. In an arrangement, themechanical connector is a two-piece connector having a first piece(e.g., first connector) attached to an upper portion of the mandrel bodyand a second piece (e.g., second connector) attached to the upper end ofthe casing engagement body. When the upper mandrel is disposed (e.g.,compressed) towards the upper end of the casing engagement body, thefirst and second connectors mechanically engage locking the mandrel bodyin the lowered position. Any mechanical connector may be utilized.

In one aspect, a first connector is attached to the axial rod proximateto a connection point between the upper mandrel and the axial rod. In anarrangement, the first connector is a split ring connector that fitsover the axial rod. In such an arrangement, split ring connector has agenerally cylindrical body with a hollow interior and a split/slitextending along the entire length of its sidewall. An outside surface ofthe split ring connector may include a plurality of serrations (e.g.,annular ridges and valleys). Such serrations may be configured to engagea plurality of mating grooves (e.g., annular ridges and valleys) formedin the central aperture of the upper end of the casing engagement body.An inside diameter of the split ring connector may have a diameter thatis greater than an outside diameter of the axial rod. This increaseddiameter permits the split ring connector to compress when theserrations engage the grooves in the upper end (e.g., about theperiphery of the central aperture) of the casing engagement body. Thisallows the serrations to pass over at least a portion of the grooveslocking the mandrel body to the casing engagement body. The serrationsand grooves may be configured to permit unidirectional movement. In afurther arrangement, the first connector includes a plurality ofserrations integrally formed on an outside surface of the axial rod. Inthis arrangement, the serrations of the axial rod engage a plurality ofgrooves formed in the central aperture of the upper end of the casingengagement body. In such an arrangement, a split ring connector may bedisposed within the central aperture. Alternatively, the centralaperture may include an axial slot to permit the central aperture toflex when engaged by the serrations of the axial rod.

In an arrangement, the split ring connector is attached to the axial rodvia a shear pin. Such a shear pin permits separating the axial rod formthe split ring connector when an axial force is applied to the uppermandrel (e.g., by a wireline device). This allows removing the collarstop from the production tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a production tubing is disposedwithin a casing of an oil and gas well.

FIG. 2A is a perspective view of a prior art collar stop.

FIGS. 2B-2D illustrate the operation and installation of the collar stopof FIG. 2A.

FIG. 3A is a perspective view of a locking collar stop in accordancewith the present disclosure.

FIG. 3B is an exploded view of the collar stop of FIG. 3A.

FIGS. 4A and 4B show side and side cross-sectional views, respectively,of a collar stop in an open position.

FIG. 4C shows a side cross-sectional view of a collar stop in a closedand locked position.

FIG. 5 shows a perspective view of a two-piece connector for locking thecollar stop in a closed position.

FIG. 6 shows a close up view of the two-piece connector locking thecollar stop in the closed position.

FIG. 7 illustrates an alternate embodiment of a locking collar stop inaccordance with the present disclosure.

DETAILED DESCRIPTION

Reference will now be made to the accompanying drawings, which at leastassist in illustrating the various pertinent features of the presentedinventions. The following description is presented for purposes ofillustration and description and is not intended to limit the inventionsto the forms disclosed herein. Consequently, variations andmodifications commensurate with the following teachings, and skill andknowledge of the relevant art, are within the scope of the presentedinventions. The embodiments described herein are further intended toexplain the best modes known of practicing the inventions and to enableothers skilled in the art to utilize the inventions in such, or otherembodiments and with various modifications required by the particularapplication(s) or use(s) of the presented inventions.

A typical installation plunger lift system 50 can be seen in FIG. 1. Thesystem includes what is termed a lubricator assembly 10 disposed on thesurface above a well bore including casing 8 and production tubing 9.The lubricator assembly 10 is operative to receive a plunger 100 fromthe production tubing 9 and release the plunger 100 into the productiontubing 9 to remove fluids (e.g., liquids) from the well. Fluidaccumulating above of the plunger 100 at the bottom of the well may becarried to the top of the well by the plunger 100. Specifically, afterpassing through the liquids at the bottom of the well, gasses accumulateunder the plunger lifting the plunger and any fluid above the plunger tothe surface. The lubricator assembly 10 controls the cycling of theplunger into and out of the well. The exemplary lubricator assembly 10includes a cap 1, top bumper spring 2, striking pad 3, and a receivingtube 4, which is aligned with the production tubing. When utilized witha bypass plunger, the lubricator may further include a rod 17 that mayextend through a plunger received by the lubricator to open a bypassvalve or valve element of the plunger.

Surface control equipment usually consists of motor valve(s) 14, sensors6, pressure recorders 16, etc., and an electronic controller 15 whichopens and closes the well at the surface. Well flow ‘F’ proceedsdownstream when surface controller 15 opens well head flow valves.Controllers operate based on time, or pressure, to open or close thesurface valves based on operator-determined requirements for production.Alternatively, controllers may fully automate the production process.

In some embodiments, the lubricator assembly 10 contains a plunger autocatching device 5 and/or a plunger sensing device 6. The sensing device6 sends a signal to surface controller 15 upon plunger 100 arrival atthe top of the well and/or dispatch of the plunger 100 into the well. Amaster valve 7 allows for opening and closing the well. Typically, themaster valve 7 has a full bore opening equal to the production tubing 9size to allow passage of the plunger 100 there through. The bottom ofthe well is typically equipped with a seating nipple/tubing stop 12. Aspring standing valve/bottom hole bumper assembly 11 may also be locatednear the tubing bottom. The bumper assembly or bumper spring is locatedabove the standing valve and can be manufactured as an integral part ofthe standing valve or as a separate component.

FIG. 1 illustrates a plunger lift system 50 as installed in a verticalwell where a seating nipple is installed at the bottom of the well. Insuch an arrangement, the plunger cycles between the bottom hole assembly(e.g., seating nipple and spring) and the lubricator assembly. However,in a number of situations, a seating nipple is not installed or isinstalled at a location that will not work for plunger lift. Forinstance, lateral wells have a vertical section that extends from thesurface and transitions to a horizontal section. Typically, plungers canonly fall to about 40-60 degrees from vertical. Nonetheless, suchlateral wells can benefit from plunger lift. To permit use of plungerlift in lateral wells or in wells lacking a seating nipple, atemporary/removable bottom assembly or ‘collar stop’ may be inserted ata desired location within the well (e.g., in a vertical or mostlyvertical section of a lateral well). This collar stop may form a bottomhole assembly at a desired location within the well.

FIGS. 2A-2D illustrates one embodiment of a prior art collar stop 110.The collar stop 110 is configured for insertion into well productiontubing where it provides an interference fit with a collar recessdisposed between two adjacent sections of production tubing. As shown inFIG. 2A, the collar stop 110 is a generally cylindrical device having amandrel body 112 and a casing engagement body 120. The mandrel bodyincludes upper and lower mandrels 114, 116, respectively, connected byan axial rod 118, which is disposed through the casing engagement body120. The casing engagement body 120 is configured to engage a casingrecess to lock the collar stop in production tubing at a desiredlocation, as further described herein.

As shown, the upper mandrel 114 and lower mandrel 116 each have adiameter that is larger than a diameter of the axial rod 118, whichpasses through (e.g., is slidably received within) an aperture formed inof a top end of the casing engagement body 120. In the illustratedembodiment, the top end of the casing engagement body 120 is a generallyannular element having a central aperture, which extends there through,and is referred to herein as an ‘annular ring’ 122. However, it will beappreciated that the annular ring 122 need not be strictly annular inshape. What is important is that the annular ring 122 forms an upper ortop end of the casing engagement body and includes an aperture (e.g.,central aperture) for slidably receiving the axial rod 118 of themandrel body 112. Diameters of the upper mandrel 114 and lower mandrel116 are larger than the diameter of the central aperture extendingthrough the annular ring 122. Accordingly, once the axial rod 118 isdisposed through the central aperture of the annular ring 120, themandrel body 112 may slide through the annular ring 120 between a bottomend 115 of the upper mandrel 114 and an upper end 117 of the lowermandrel 116. That is, the mandrel body 112 moves relative to the casingengagement body 120.

The casing engagement body 120 further includes first and second legs orarms 124 a, 124 b (hereafter 124 unless specifically referenced) thatextend from a lower end of the annular ring 122. That is, the arms 124cantilever from the lower end of the annular ring 122. The lower mandrel116 is disposed between the inside surfaces of the arms 124. Disposedproximate to the free end of each of the arms 124 on their outsidesurfaces are casing engagement tabs 126 a, 126 b (hereafter 126 unlessspecifically referenced). Also attached to lower end of each arm 124 aretripwires 128 a, 128 b (hereafter 128 unless specifically referenced).The tripwires 128 are configured to hold the arms 124 toward one anotherwhen the arms are deflected to permit inserting the collar stop 110 intoproduction tubing. More specifically, the tripwires are pivotallyattached near the free ends of the arms 124 and configured to hold thefree ends of the arms 124 toward one another (See FIGS. 2A and 2B), in afirst position, and release the free ends of the arms 124 (See. FIG.2C), in a second position.

When the tripwires 128 hold the free ends of the arms 124 together, anoutward diameter measured between opposing outside surfaces of thecasing engagement tabs 126 is reduced to a dimension that is less thanan inside diameter of production tubing in which the collar stop 110 isinserted. This allows lowering the collar stop 110 downward throughproduction tubing. Along these lines, the upper mandrel 114 may includea fishing neck 108, which may comprise a standard American PetroleumInstitute (API) fishing neck. The fishing neck 108 may be engaged by awireline device (not shown), as known by those skilled in the art. Thewireline lowers the collar stop through the production tubing to adesired location while the tripwires 128 hold the free ends of the arms124 toward one another/together. Once lowered to a desired depth, thewireline raises the collar stop 110 until free ends 129 of the tripwires128 engage a collar recess between adjacent joints of production tubing.That is, when pulled upward, the tripwires snag on a collar recess 140formed by a collar 144 connecting adjacent sections of production tubing146. See, e.g., FIG. 2D. This releases the tripwires freeing the arms124, which expand outward. The collar stop 110 may then be raised orlowered until the casing engagement tabs 126 encounter the collar recess140. See FIG. 2D. The cantilevered arms 124 press the engagement tabs126 into the recess 140.

Once the engagement tabs 126 are engaged with the collar recess 140, themandrel body 112 is pushed downward until the lower mandrel 116 ispositioned between lower portions of the arms 124, which prevents thearms from flexing inward. See FIG. 2D. This locks the casing engagementtabs 126 in the collar recess 140. To maintain the mandrel body 112 inthe lowered position (See FIG. 2D), the lower mandrel 116 is pusheddownward until its upper end 117 is disposed below locking tabs 130 a,130 b formed in the inside surfaces of the arms 124. This engagementhelps maintain the mandrel body 112 in the lowered position andmaintains the collar stop 110 in place. Once secured in position, theupper end of the collar stop 110, may then support other components(e.g., bumper springs etc.). Such components may engage the fishing neckto secure them to the collar stop 110. Of further note, the mandrel body112 includes an axial passageway 106 that permits well fluids to passthrough the collar stop 110, when secured within the production tubing.

The collar stop 110 may be removed by engaging the fishing neck 108 andlifting the mandrel body 112. This removes the lower mandrel 116 frombehind the arms 124 permitting the arms 124 to flex such that theengagement tabs 126 may move inward and out of the collar recess 140disengaging the collar stop 110 from the collar recess. The collar stopmay then be lifted to the surface.

Aspects of the present disclosure are based on the realization that incertain wells with high flow rates, the flow of fluids through the axialpassageway 106 of the mandrel body 112 tends to dislodge or lift themandrel body 112 from the lowered position. That is, such high fluidflows move the mandrel body 112 upward releasing the engagement tabs 126of the casing engagement body 120. In such situations, high fluid flowslift the collar stop 110 to the surface. To counteract such high flowconditions, the presented collar stop utilizes a locking connector whichlocks the axial rod 118 of the mandrel body 112 to the annular ring 122of the casing engagement body 120 when the mandrel body is in thelowered position.

FIGS. 3A and 3B illustrate one embodiment of a locking collar stop 210in accordance with the present disclosure. As illustrated, the lockingcollar stop 210 shares numerous component as the prior art collar stopdescribed in relation to FIGS. 2A-2D and common reference numbers areutilized to refer to common components. The locking collar stop 210incudes a mandrel body 112 that moves relative to a casing engagementbody 120. More specifically the mandrel body 112 includes upper andlower mandrels 114, 116 connected by an axial rod 118 while the casingengagement body 120 incudes an annular ring 122 having first and secondarms 124 a, 124 b (hereafter 124 unless specifically referenced) thatcantilever from a lower end of the annular ring 122. The axial rod 118passes through the annular ring permitting the mandrel body 112 to moverelative to the casing engagement body 120. Likewise, the arms 124 eachinclude casing engagement tabs 126 a, 126 b (hereafter 126 unlessspecifically referenced) on their outside surfaces disposed near theirfree ends. Tripwires 128 a, 128 b (hereafter 128, specificallyreferenced) are also attached near the free ends of the arms for use indeflecting and holding the arms 124 toward one another as illustrated inFIG. 3A. The arms also include locking tabs 130 a, 130 b formed theirinside surfaces for engaging the upper end of the lower mandrel 116 whenthe mandrel body 112 is in the lowered position. The locking collar stop210 is inserted into production tubing in a manner that is substantiallysimilar to the process described in relation to FIGS. 2B-2D.

As best shown in FIGS. 3A-4B, the locking collar stop 210 furtherincorporates a locking connector which mechanically engages (e.g.,locks) the axial rod 118 of the mandrel body 112 to the annular ring 122of the casing engagement body 120, when the mandrel body 112 is in theclosed position. In the illustrated embodiment, the locking connector isa two-piece connector having a first connector attached to the mandrelbody 112 and a second connector (e.g., mating connector) attached to thecasing engagement body 120. In the illustrated embodiment, the firstconnector is split ring connector 150 that is disposed about the axialrod 118 proximate to the point of connection between the axial rod 118and the upper mandrel 114. As illustrated, the split ring connector 150is attached to the axial rod 118 via a shear pin 152 that passes throughan aperture 154 in a sidewall of the split ring connector 150 andextends into a mating aperture 155 in the axial rod 118. See FIG. 3B. Inthe illustrated embodiment, the second connector is formed within thecentral aperture of the annular ring 122, as more fully discussedherein.

FIG. 5 shows a close up view of the split ring connector 150 and themating connector 160 formed within the central aperture 124 of theannular ring. As shown, the split ring connector 150 is a generallycylindrical and hollow element having a sidewall sized to fitover/around an outside surface of the axial rod. The outside surface ofthe sidewall of the connector 150 has a series of serrations (e.g.,annular grooves) 156. This serrated outside surface (e.g., sawtoothsurface) of the split ring connector 150 is configured for receiptwithin mating serrations 160 (e.g., second connector) formed in theinterior surface of the annular ring 122. That is, the inside peripheralsurface of the central aperture 123 includes serrations/grooves 160 thatare configured to mate with the serrations 156 on the outside surface ofthe split ring connector 150. Of note, the inside diameter ‘ID’ of theconnector 150 is slightly larger than the outside diameter ‘OD’ of theaxial rod such that the split ring connector 150 may compress slightly.See, e.g., FIG. 6. That is, a split 158 extending along the entirelength of a sidewall of the connector 150 allows for slightlycompressing the connector 150 around the axial rod. Accordingly, whenthe connector 150 is forced into the central aperture 123 of the annularring 122, the split ring connector 150 may compress such that theserrations 156 on its outside surface may pass over the serrations 160formed on the inside surface of the annular ring 122.

FIGS. 4A-4C illustrate the locking collar stop 210 in open and lockedconfigurations. More specifically, FIGS. 4A and 4B illustrates a sideview and a cross-sectional side view, respectively, of the collar stop210 in an open configuration while FIG. 4C illustrates a cross-sectionalside view of the collar stop in a closed and locked configuration. Asillustrated, when the mandrel body 112 moves from the open configuration(e.g., FIG. 4B) to the closed configuration (e.g., FIG. 4C) the splitring connector 150 is forced into the central aperture of the annularring 120 such that the serrations 156 of the connector 150 mate with theserrations 160 of the annular ring 122. This is best illustrated in FIG.6, which shows a close up of the engagement of the split ring connector150 and the annular ring 122. As shown in FIG. 6, the serrations 156 and160 may be shaped to permit unidirectional movement of the split ringconnector 150 into the annular ring 122. Once the serrated surfaces areengaged, the mandrel body 112 is locked in the lowered/closed position.

In application, the locking collar stop 210 is positioned in productiontubing such that the collar engagement tabs are disposed within a collarrecess (See, e.g., FIG. 2D). Once the engagement tabs are engaged withthe collar recess, the mandrel body 112 is pushed downward until thelower mandrel 116 is positioned between a lower portion of the arms 124,which prevents the arms from flexing inward. The force(s) applied to themandrel body 112 also forces the split ring connector 150 into theaperture of the annular ring 122 locking the collar stop 210 in place.Once locked, the collar stop is able to withstand high fluid flowpassing through its axial passageway 106 that tend to dislodge the priorart collar stops.

Once the locking collar stop is locked with the split connector engagedwith the annular ring, the locking collar stop 210 is highly resistantto removal. However, most collar stops are designed for periodic removalfrom production tubing. To allow removal of the locking collar stop 210,the split ring connector is attached to the axial rod via the shear pin152 (e.g., set screw) that passes through an aperture in a sidewall ofthe split ring connector 150 and extends into a mating aperture 156 inthe axial rod 118. See. FIG. 6. The shear pin 152 is typically formed ofa material having a hardness and shear strength that is significantlyless that the hardness and shear strength of the axial rod 118 and splitring connector 150. In a non-limiting embodiment, the shear pin may beformed from brass while the axial rod and split ring connector areformed of steel (e.g., stainless steel). Other materials are possible.To remove the locking collar stop 210, a wireline attaches to thefishing neck and applies an upward force to the mandrel body. Thisupward force shears the shear pin freeing the axial rod 118 from thesplit ring connector 150. The mandrel body 112 may then be moved upwardremoving the lower mandrel 116 from behind the arms 124 permitting thearms 124 to flex such that the engagement tabs 126 may move inward outof the collar recess 140 and thereby allowing the locking collar stop210 to be lifted to the surface.

FIG. 7 illustrate another embodiment of a locking collar stop 310 inaccordance with the present disclosure. As illustrated, the lockingcollar stop 310 shares numerous component as the prior art collar stopdescribed in relation to FIGS. 3A-6 and common reference numbers areutilized to refer to common components. The locking collar stop 310incudes a mandrel body 112 that moves relative to a casing engagementbody 120. More specifically the mandrel body 112 includes upper andlower mandrels 114, 116 connected by an axial rod 118 while the casingengagement body 120 includes an annular ring 122 having first and secondarms 124 a, 124 b (hereafter 124 unless specifically referenced) thatcantilever from a lower end of the annular ring 122. The axial rod 118passes through the annular ring permitting the mandrel body 112 to moverelative to the casing engagement body 120. Likewise, the arms 124 eachinclude casing engagement tabs 126 a, 126 b (hereafter 126 unlessspecifically referenced) on their outside surfaces disposed near theirfree ends. The locking collar stop 310 is inserted into and removed fromproduction tubing as described above.

As illustrated, in the embodiment of FIG. 7, the upper mandrel 114further includes a bumper spring 180. That is, as opposed to the uppermandrel 114 terminating in a fishing neck 108, the upper mandrel mayfurther include one or more components, such as the bumper spring 180.In such an embodiment, rather than placing the locking collar stopwithin production tubing and then utilizing the fishing neck of thelocking collar stop to attach one or more components to the lockingcollar stop, such components may be placed within the production tubingwith the collar stop. These components may be integrally formed orotherwise connected to the collar stop. Further, it will be appreciatedthat various different components may be attached to the upper mandrel.

The foregoing description has been presented for purposes ofillustration and description. Furthermore, the description is notintended to limit the inventions and/or aspects of the inventions to theforms disclosed herein. Consequently, variations and modificationscommensurate with the above teachings, and skill and knowledge of therelevant art, are within the scope of the presented inventions. Theembodiments described hereinabove are further intended to explain bestmodes known of practicing the inventions and to enable others skilled inthe art to utilize the inventions in such, or other embodiments and withvarious modifications required by the particular application(s) oruse(s) of the presented inventions. It is intended that the appendedclaims be construed to include alternative embodiments to the extentpermitted by the prior art.

What is claimed is:
 1. A locking collar stop device, comprising: acasing engagement body having an upper end with a central aperture andfirst and second arms that cantilever downward from opposing sides ofthe upper end, each arm having a casing engagement tab formed on anoutside surface proximate to a free end of the arm; a mandrel bodyhaving an upper mandrel, a lower mandrel and an axial rod extendingbetween and connecting the upper mandrel and the lower mandrel, whereinthe lower mandrel is disposed between inside surfaces of the first andsecond arms, the axial rod is slidably received through the centralaperture and the upper mandrel is disposed above the upper end of thecasing engagement body; a first connector disposed on the mandrel bodyproximate to a point of connection between the upper mandrel and theaxial rod; and a second connector disposed on the upper end of thecasing engagement body; wherein the first and second connectormechanically connect when the upper mandrel is disposed proximate to theupper end of the casing engagement body.
 2. The device of claim 1,wherein the mandrel body is configured to move relative to the casingengagement body between a lower surface of the upper mandrel and anupper surface of the lower mandrel.
 3. The device of claim 2, whereinthe first connector comprises: a split ring connector disposed about anoutside surface of the axial rod.
 4. The device of claim 3, wherein thesplit ring connector comprises: a cylindrical body having: a generallycylindrical sidewall; a plurality of serration formed about an outsidesurface of the sidewall; and an axial split extending along an entirelength of the sidewall.
 5. The device of claim 4, wherein the secondconnector comprises: a plurality of grooves formed on an insideperipheral surface of the central aperture, wherein the serrations ofthe split ring connector are sized to engage the grooves of the centralaperture.
 6. The device of claim 4, wherein an inside diameter of thesplit ring connector is greater than an outside diameter of the axialrod.
 7. The device of claim 4, wherein the split ring connector isconnected to the axial rod via a set screw.
 8. The device of claim 7,wherein the set screw comprises a shear pin having a hardness that isless than a hardness of the axial rod and less than a hardness of thesplit ring connector.
 9. The device of claim 2, wherein the uppermandrel further comprises: a fishing neck.
 10. The device of claim 2,wherein each arm further comprises: a tripwire pivotally attachedproximate to the free end of the arm.
 11. A locking collar stop device,comprising: a casing engagement body having: an annular ring with acentral aperture extending through the annular ring, an inner peripheryof the central aperture having a plurality of grooves; first and secondarms that cantilever downward from opposing sides of the annular ring,each arm having a casing engagement tab formed on an outside surfaceproximate to a free end of the arm; a mandrel body having: an uppermandrel; a lower mandrel; an axial rod extending between and connectingthe upper mandrel and the lower mandrel, wherein the lower mandrel isdisposed between inside surfaces of the first and second arms, the axialrod is slidably received through the central aperture and the uppermandrel is disposed above the upper end of the casing engagement body;and a serrations disposed about an outside surface of the axial rodproximate to a point of connection between the upper mandrel and theaxial rod, wherein the serrations mechanically engage at least a portionof the plurality of grooves of the central aperture when the uppermandrel is compressed against the annular ring.
 12. The device of claim11, wherein the serrations are formed on a split ring connector disposedabout an outside surface of the axial rod.
 13. The device of claim 12,wherein the split ring connector comprises: a cylindrical body having: agenerally cylindrical sidewall, wherein the serrations are formed aboutan outside surface of the sidewall; and an axial split extending alongan entire length of the sidewall.
 14. The device of claim 14, wherein aninside diameter of the split ring connector is greater than an outsidediameter of the axial rod.
 15. The device of claim 13, wherein the splitring connector is connected to the axial rod via a set screw.
 16. Thedevice of claim 15, wherein the set screw comprises a shear pin having ahardness that is less than a hardness of the axial rod and less than ahardness of the split ring connector.